Aerodynamic wave machine port lead edge modification for extended speed range



Jan. 22, 1963 AERODYNAMIC WAVE MACHINE PORT LEAD EDGE ENG/NE '1T 5#fm/fr Paar c 4/ al1/E L cya; I

LA aunar )0027/4 MODIFICATION FOR EXTENDED SPEED RANGE Filed March 29,1960 3 Sheets-Shawl'.4 1

Jan. 22, 1963 M. BERcHToLD 3,074,622

AERODYNAMIC WAVE MACHINE PORT LEAD EDGE MODIFICATION FOR EXTENDED SPEEDRANGE Filed March 29, 1960 3 Sheets-Sheet 2 ...FG-:5%- If-E: Eb.

HP /IVLE 7' 35%.. lunga-mann 3.f% ,egg/W. 4a .ll/.M 7,45? HH/W.

INVENTOR. Max aina/170201.

BY y Zw-nn Awa, fase/651m i JaFff/v,

Jan. 22, 1963 M. ar-:RcHToLD 3,074,622

AERODYNAMIC WAVE MACHINE PORT LEAD EDGE MODIFICATION FOR EXTENDED SPEEDRANGE IN1/mmm MA x afec/Wow' l I l I l l I l l 35% 0% 75% /aa% d/IUnited States Patent() AERODYNAMIC WAVE MACHINE PORT LEADlllilgllg/IODIFICATION FOR EXTENDED SPEED Max Berchtold, Kusnacht,Switzerland, assignor to I-T-E Circuit Breaker Company, Philadelphia,Pa., a corporation of Pennsylvania Filed Mar. 29, 1960, Ser. No. 18,3842 Claims. (Cl. 230-69) My invention relates to pressure exchangers usedas superchargers for combustion engines and more particularly isdirected to the configuration of the leading sections of the portslocated in the high pressure cycle to minimize the detrimental effectsof reflected waves created as a result of mis-timing during low speedoperation.

With my novel configuration of the leading portion of the high pressureports it is possible to `have a higher efficiency of the pressureexchanger over a wide speed range of operation and in particular permita larger output of air and improved efficiency at low speeds.

The operation of an aerodynamic wave machine or pressure exchangerutilized in my instant invention is disclosed and illustrated inco-pending United States applications Serial Number 454,774, filedSeptember 8, 1954 to Max Berchtold for Wave Engine now U.S. Patent2,970,745 issued February 6, 1961; Serial Number 458,771, tiledSeptember 28, 1954 to Max Berchtcld for Aerodynamic Wave Machine as aSupercharger for Reciprocating Engines now U.S. Patent 2,957,304 issuedOctober 25, 1960; Serial Number 647,091, filed March 19, 1957 to ErnstNiederrnann for Reverse Cycle Aerodynamic Wave Machine now U.S. Patent2,959,340 issued November 8, 1960; Serial Number 637,570 filed January31, 1957 to Max Berchtold and Ernst Niedermann for Diesel EngineSupercharged by the Aerodynamic Wave Machine now abandoned; SerialNumber 799,285, filed March 13, 1959 to Max 'Berchtold for Wide SpeedRange Pressure Exchanger Supercharger now U.S. Patent 3,012,708 issuedDecember l2, 1961 and Serial Number 742,601 led June 17, 1958 to MaxBerchtold for Adjustable Stator Plate for Variable Speed AerodynamicWave Machine now U.S. Patent 3,011,487 issued December 5, 1961, all ofwhich are assigned to the assignee of the instant application.

Many prior art constructions have been proposed -in order to increasethe efficiency and maintain required mass-flow of the pressure exchangerwhen it is operated at speeds other than its design speed. One suchmethod is to provide an angularly adjustable plate such as shown inaforementioned application Serial No. 742,601. Also prior arrangementshave been suggested whereby the position of the edges of the ports havebeen changed in order to increase efficiency, such as disclosed inaforementioned applications, Serial Numbers 647,091 and 799,285.

In the operation of an aerodynamic wave machine, it is usually necessaryto have a drive or control means to provide timing for the waves. If theaerodynamic wave machine is used as a supercharger, it is mostadvantageous to obtain the necessary power to drive the pressureexchanger from the reciprocating combustion engine. This can be achievedby any number of means, such as a belt drive, hydraulic drive,electrical drive, etc. The most economical and simple of these is thestandard V belt drive. However, since most reciprocating combustionengines operate over a range of engine speed the pressure exchangerspeed deviates at certain operating speeds from optimum conditions andefficiency may, therefore, be substantially decreased due to mis-timingof the waves.

ICC

Although lit is desirable to have the aerodynamic wave machinesupercharger driven at a constant speed independent of the reciprocatingengine speed, in practice, the speed, and thus the mass-flowrequirements, of the reciprocating engine vary and hence the prior artfixed drive aerodynamic wave machine would not be eflicient through theentire speed range of the reciprocating engine.

However, with a simple and therefore desirable belt drive from thereciprocating engine to the aerodynamic wave machine, it is not possibleto operate the pressure exchanger within the eflicient speed range. Atlow engine speed particularly it is desirable to maintain a high airmanifold pressure which cannot be obtained at low speed of the pressureexchanger since the timing of the waves is upset to such an extent, thatthe required exhaust temperature exceeds the available exhausttemperature.

ln aforementioned copending application Serial No. 742,601, there isshown an arrangement whereby the variable speed drive from thecombustion engine to the pressure exchanger is utilized and the pressureexchanger is provided with a continuously adjustable stator plate sothat the ports are constantly being angularly repositioned to ensureproper timing at all speeds. This arrangement provides maximumefliciency over the speed range of the pressure exchanger. However, thisis achieved at the sacrifice of a rather complicated mechani calconstruction which not only adds expense to the pressure exchanger, butalso increases the mechanical failures, inspection, maintenance andadjustments.

With my present invention, the eflciency is reduced over the range ofspeed operation when compared to the adjustable plate arrangement, buthas a higher efiicency over low range of speed operation than otherprior art wave machines or pressure exchangers.

My present invention is particularly directed to a pressure exchangerfor supercharging an internal combustion engine in which it is desirableto drive the pressure exchanger by a simple belt or fixed gear rotordrive directly from the internal combustion engine, thereby requiringoperation of the pressure exchanger over a wide speed range. l

I achieve this by a modification of the shape of the leading controllingedges of the high pressure ports.

During low speed operation of the internal combustion engine and thepressure exchanger themain compression Wave created at the leadingcontrolling edge of the high pressure inlet port is mis-timed withregard to the leading controlling edge of the high pressure outlet port.This results in a very strong reflected wave being created in the rotorwhich has the effect of either slowing down, stopping or reversing theilow of fluid from the high pressure inlet port into the rotor. However,if the leading controlling edge of the high pressure outlet port isproperly shaped, the high pressure iluid created by the mis-timed waveis permitted to escape through the area formed by the stator and therotor as a result of the flared portion ofthe leading edge. Thisdesirable escape or leakage of the Ihigh pressure fluid through thellared controlling edge results in a substantially reduced magnitude ofthe reilection wave.

It is noted that my invention can be applied to either the lea-ding edgeof the high pressure outlet port, or the leading edge of the highpressure inlet port or to both of the ports. The leading edge of thehigh pressure inlet port is Iflared out inorder to create a more.gradually increasing main compression wave which at the leading sectionof the inlet port will result in substantially reduced reflection wavesspecifically in the case of extreme mis-timing at low speed of thepressure exchanger. Thus when the modified edge of the high pressureinlet port is used in coniunction with the modifiedv edge of the highpressure outlet port, there is a very effective arrangement for reducingthe deleterious effects of the reiiected waves.

It is noted that when both the inlet and the outlet ports have a gradualopening of the leading edge, the pressure exchanger has extremelydesirable operation near the design speed. That is during normaloperation (i.e. near design point) the gradual build up of pressure inthe compression wave, due to the gradual opening of the high pressureinlet port matches the gradual opening of the high pressure inlet portand as a result thereof the overall losses due to the partial opening ismaintained constant.

Accordingly, a primary object of my invention is to provide a novelarrangement whereby the modified controlling edges of the high pressureports substantially reduces the magnitude of the re'ected waves createdduring mis-timing.

Another object of my invention is to provide an iinproved controllingedge for the high pressure ports to thereby reduce the reflection of thecompression wave at low speed performances of the pressure exchanger.Another object of my invention is to provide a novel structuralconfiguration for the leading edges of the high pressure ports to reducethe outflow at the high pressure inlet port and also reduce the in-liowfrom the high pressure outlet port.

Still a further object of my invention is to provide a pressureexchanger whereby the configuration of the controlling edges permits alarger output of air at low speeds at an improved efficiency to therebypermit a better matching of the pressure exchanger and the internalcombustion engine supercharged and driven thereby.

These and other objects of my invention will be apparent from thefollowing description when taken in connection with the drawings inwhich:

FIGURE 1 is a schematic representation of a pressure exchangersupercharging a combustion engine and shows a direct drive such as beltdrive from the reciprocating combustion engine to the pressureexchanger.

FIGURE la is a schematic perspective view of a pressure exchanger havingreverse cycle with two cycles per revolution. This figure illustratesthe rotor and ports within the stationary stator plates.

FIGURE 2a is a partial schematic view of the rotor and ports showing theconditions of the iiuids in the high pressure position of the cycle withthe rotor driven at 35% of maximum r.p.m.

FIGURE 2b is a partial schematic view of the rotor and ports showing thecondition of the fluids in the high pressure portion of the cycle withthe rotor driven at 75% of maximum r.p.m. which is design speed. Thisfigure corresponds to the high pressure portion of FIG- URE 5.

FIGURE 3a is a view similar to FIGURE 2a but shows the condition withinthe rotor when the leading edge of the high pressure outlet port D ismodied to flare out in accordance with my invention.

FIGURE 3b is a view similar to FIGURE 2b of the machine modified asnoted in FIGURE 3a.

FIGUREAa is a view similar to FIGURES 2a and 3a but shows the conditionwithin the rotor when the leading edge of both high pressure ports(inlet and outlet) are modied in configuration in accordance with myinvention.

FIGURE 4b is a view similar to FIGURES 2b and 3b of the machine modifiedas noted in FIGURE 4a.

FIGURE 5 is a schematic developed View of the rotor and port showing thecondition of the liuids in each section of the rotor having reversecycle operation. rIhis view illustrates the cycle of operation at priorart design conditions and illustrates an ideal design cycle.

FIGURE 6 is a tabulation to compare eight conditions and show how mynovel pressure exchanger compares with prior art pressure exchangers.

FIGURE 6a is a graphic illustration of the tabulation in FIGURE 6plotting pressure exchanger air mass flow vs. reciprocating combustionengine 1'.p.rn. and illustrates the relationship for nine differentconditions between the requirements of a reciprocating engine and thatactually delivered by an aerodynamic wave machine used as asupercharger.

Referring to FIGURE l, there is shown a schematic representation of apressure exchanger 10 having a low pressure inlet port B for fresh air,a low pressure outlet port A to exhaust the =hot gases, a high pressureoutlet port D to supply compressed air through duct 12 to the combustionengine 11, and a high pressure inlet port C which supplies the pressureexchanger with high pressure exhaust gases from the combustion engine 11fed through the duct 13. The drive shaft 14 of the combustion engine 11has a pulley 16 and the drive shaft 15 of the pressure exchanger 10 hasa pulley 17.

The direct drive from the combustion engine 11 to the rpressureexchanger 10 is achieved by the belt 18 which transmits shaft power frompulley 16 to pulley 17. The ratio of the `direct drive can be achievedby various size pulleys. Any other means well known in the art can beused for this drive purpose.

Thus referring first to FIGURES 1 and la, the rotor 30 of the pressureexchanger I@ is driven for rapid rotation about its axis by means suchas a belt drive l from the combustion engine 11 placed over the pulley17 of the rotor shaft 15. The manner in which the exhaust gases from thecombustion engine are supplied to the pressure exchanger 10 and themanner in which the compressed air from the pressure exchanger 1% issupplied to the cornbustion engine 11 is illustrated and described inaforementioned Vcopending U.S. application Serial Number 458,771. Therotor 3f) has an outer shroud 33` and a plurality of channels or cells35. The cold stationary stator plate 4f) is placed at one end of therotor 36- and the hot stationary stator plate 41 is placed at the otherend of the rotor 30 in the closest possible proximity thereto consistentwith both high speed rotation required in the rotor as Well asvariations due to expansion of the parts and still maintain the bestpossible fluid tight seal. The stationary stator plate 41 on the rightside of the rotor 3f) is provided with high pressure inlet port C forthe input of a first fluid at elevated pressure and temperature and alow pressure outlet port A for exhausting the yfirst fluid atapproximately ambient pressure. Stationary stator plate 46' on the leftof rotor 3f) is provided with a high pressure outlet port D for theoutput of a second fluid at elevated pressure, which tiuid is thecompressed air supplied to the combustion engine 11, and low pressureinlet port B for the intake of the second fiuid at ambient pressure.

Since rotor 3d' of the pressure exchanger 10 is belt driven from thecombustion engine 11 it rotates with a variable speed proportional tothat of the combustion engine but as will hereinafter be more fullydescribed our instant invention provides a novel configuration of theleading edges of the high pressure ports to reduce the undesirableeffects of mis-timed waves.

As individual channels or cells of the rotor 30 of the prior artpressure exchanger move successively past opposite ports C and D andthen A and B, the creation and propagation of the various waves as wellas the pressure interchanges and interfaces which occur are demonstratedin a development View of FIGURE 5. A detailed analysis of the cycle ofoperation is set forth in aforementioned copending application SerialNumber 454,774. It is noted that FIGURE 5 represents the ideal cycle ofoperation. Thus the pressure exchanger has been' designed for maximumefficiency at the rotor speed of FIGURE 5, i.e. design speed.

Within the high pressure State I the opening or leading edges 5 and 6 ofthe high pressure inlet port C and high pressure outlet port D arephysically related to each other and the closing or trailing edges 7 and8 are physically related to each other. 'Ihe cycle of operation isessentially independent ot the length of time during which the lluidremains at State II and there is no relation between the pair of portsC, D of the high pressure stage and the pair of ports A, B of the lowerpressure stage.

FIGURE 5 illustrates an example of an ideal condition of the prior artin which there is complete high and low pressure scavenging of thepressure exchanger 10. The action of the Waves can also be studied inFIGURE 5 by cutting a narrow slot in a piece of paper to represent atypical channel or cell 35 and sliding this slot transversely downFIGURE 5. In the illustration the rst fluid, which represents the hotgas exhaust from the combustion engine 1I, is represented by the dottedarea, and the second uid, which is the compressed air output of thepressure exchanger, r into the combustion engine l1, is represented bythe unmarked area. The movement of the uid is indicated by the arrows.

The second uid can be at ambient pressure and is always present at thelow pressure inlet port B, and the first fluid is always present at thehigh pressure inlet port C. The cells 35 in the rotor 30 arecontinuously moving past the ports A, B, C and D and the closed spacesbetween the ports in the stator plate 40 and the stator plate 41. Thus,for the purposes of description, the cycle of operation may start at anypoint. At zero degree rotation the second iluid is at rest at State IVin the rotor 30. The period of time that the second tluid is at restduring State IV depends only on structural conditions and does notaffect the cycle of operation. When the channel has rotatedapproximately 10 its right end reaches the opening or leading edge 5,thereby permitting the rst fluid in high pressure inlet port C toimpinge upon the medium pressure second fluid within the rotor 30. Sincethe total pressure in the high pressure inlet port C is higher than thepressure of the second fluid in the channel, the tirst uid which leavesthe high pressure inlet port C impinges with a given velocity upon thesecond fluid within the channel and by this action compresses the secondfluid and puts it in motion. The first particles of the second uid whichare subjected to this impingement in turn push against adjacentparticles and compress them, and also put these particles in motion.This mechanism creates a compression acceleration wave CA which travelsfaster than the second fluid now set in motion. The second uid ahead ofthe wave CA is still stationary, and thus at its State IV. Behind orupstream of the Wave CA both the compressed second uid and the iirst uidare in State I. Both iluids are at the same velocity and high pressurebut divided by an interface identified as HPI.

When the channels have rotated approximately the left end will reach theopening or leading edge 6 in the stationary plate 40 of the highpressure outlet port D and the relationship of the opening edge 5 to theopening edge 6 is such that all of the second iluid in the cell iscompressed. Thus only compressed second uid will be moved out into thehigh pressure outlet port D. When the channels have rotatedapproximately the right end is closed by the closing edge 8 of the highpressure inlet port C and no further particles of the rst lluid entersthe channel. Hence, the last particles of the second lluid in thechannels will expand down to a given medium pressure and thereafter thenext adjacent medium pressure particles,'which are no longer beingpushed through the channel, will expand and so on. This is the creationof an expansion deceleration wave ED which travels downstream throughthe channels and eiectively decreases both velocity and pressure. Thepressure exchanger, aerodynamic wave machine 10 is designed so that assoon as the expansion deceleration wave ED reaches the left end of thechannel the channel will have rotated 45 to thereby close ott the leftend of the channel by the closing or trailing edge 7 in the stationaryplate 40 of the high pressure outlet port D so that no first iluid atmedium pressure' Will enter the high pressure outlet port or pickup portD.

It should be noted that if an aerodynamic wave machine 10 is designedfor a specific pressure ratio such as illustrated in FIGURE 5 theopening or leading edge 5 of the high pressure inlet port or nozzle C isphysically positioned with respect to the closing or trailing edge i ofthe high pressure outlet port D so that the high pressure interface HPIwill arrive at the left end of the channel when the channel is rotated45 and thereby closed ott by the closing edge 7 of the high pressureoutlet port D and thereby prevent any iirst fluid, even though at highpressure, from entering the high pressure outlet port D.

Between approximately 45 and 60 rotation, as illustrated in FIGURE 5,i.e., after the channel has passed the high pressure outlet port D andhigh pressure inlet port C, but has not yet reached either the lowpressure inlet port B or the low pressure outlet port A, the channel isclosed at both ends by the stationary stator plate 40 and stationarystator plate 4l and the first uid is stationary in the channel at mediumpressure. The length of time that the first fluid remains at this StateII does not affect the cycle of operation.

When the channel has rotated approximately 60, as seen in theillustration of FIGURE 5, the right end of the channel is opened to theopening edge I of the low pressure outlet port A, which port is at anambient pressure lower than the pressure in the channel. Thus, anexpansion acceleration wave EA is created at the opening or leading edge1 and is propagated 'downstream through the channel.

The pressure of the first uid ahead of the wave EA is at State II,whereas the pressure behind the wave EA is at the ambient pressureexisting in the low pressure outlet port A, so that the exhaust orscavenging velocity will depend on the pressure drop through the WaveEA.

The aerodynamic wave machine l0 is designated so that as the expansionacceleration wave reaches the left hand end of the channel, the channelwill be opened by the opening edge 2 of the low pressure inlet port B atapproximately At this time the first uid in the channel is exposed atits left end to the second fluid start tlowing into the channel with thesecond uid replacing the first fluid, i.e., scavenging out the lirstuid'. This condition continues to exist until the channel has rotatedapproximately at which time the left end of the channel is closed oft bythe closing edge 4 in the stationary stator plate 40 of the low pressureinlet port B. At this time an expansion deceleration wave ED is createdat the closing or trailing edge 4, which wave travels downstream,thereby reducing the pressure of the second fluid to a pressure belowambient at State IV.

The machine is designed so that the right end of the cell is closed olfby the closing edge 3 of the low pressure outlet port A when theexpansion deceleration wave ED reaches the right end. At this time thechannel contains only the second fluid at a vacuum and is stationary,ijef, at State IV.

When the channel has rotated the complete reverse cycle operation notedabove will repeat itself as illustrated in FIGURE 5 and -the same cycleof operation can be repeated for the remaining ports during the second180 rotation.

In the description of FIGURE 5, it will be noted that the aerodynamicwave machine is operated under ideal conditions in which there is notonly proper timing of the various wavesand'interfaces, but also thedevice operates at maximum etliciency. In the description thus far, ithas been assumed that the aerodynamic wave machine is op,- erated at afixed r.p.m., which r.p.m. enables the device to operate under nearoptimum conditions.

i It is desirable to have the pressure exchanger or aero-v dynamic wavemachine 10` driven by the combustion engine 11 which it is tosupercharge. Thus, for example, some shaft energy from the combustionengine 11, can be supplied to the aerodynamic wave machine 10` byutilizing a belt drive 18 with pulleys 16 and 17. However, as

7 will hereinafter be more iuliy explained in connection With FIGURES2a, 2b, 3a 3b, 4a and 4b, the timing requirements and eiliciency of themachine will be considerably upset with variable rpm. of the combustionengine and pressure exchanger. Hence the pressure exchanger' will not beabie to satisfy the new mass i'low requirements of the combustionengine.

FIGURES 2a and 2b show the wave diagram of the high pressure stage of aprior art pressure exchanger when operated at 35% and 75% r.p.m. and inFIGURES 3a, 3b, 4a and 4b show the wave diagram of the high sure stageof a pressure exchanger with my invention.

FIGURES 2a, 3a, and 4a are at 75% rpm. so that an accurate comparisoncan be made. FIGURE 2b is, in fact, taken from the ideal cycle of FIGURE5 and shows the compression acceleration Wave CA and expansiondeceleration wave ED at design speed, i.e., 75 of maximum r.p.m. It willbe noted that wave CA which originates at the leading edge 5 of the highpressure inlet port D terminates on the leading edge 6 of the highpressure outlet port D and the wave ED which originates on the closingor trailing edge 8 of the high pressure inlet port C terminates on theclosing edge 7 of the high pressure outlet port D.

However, if the pressure exchanger is slowed down to of maximum r.p.rn.as seen in FIGURE 2a, waves CA and ED arrive at the stator plate it?ahead of the edges `6 and 7 respectively and, as illustrated, there wilibe an undesirable back-ilow from the high pressure outlet port D backinto the rotor near the closing edge 7.

The undesirable back-flow at 35% of maximum rpm. in FIGURE 2a iseliminated in my novel device as can best be seen by a comparison ofFIGURE 2a with 3a and 4a.

As seen in the comparison of FIGURES 2a and 2b, the pressure exchanger,when operated from a simple belt or xed gear ratio drive, will have itsr.p.m. varied, depending upon the speed of the combustion engine drivingthe pressure exchanger.

Although the pressure exchanger may be designed for a f that thecompression acceleration wave originated at leadi ing edge 5 willterminate at leading edge 4 when the pressure exchanger is operated atdesign speeds. In the event that the rotor r.p.rn. is substantiallyreduced as for example, from 75% of its maximum r.p.m. down to 35% ofits rpm., such as shown in the comparison of FIGURES 2b and 2c, then thecompression acceleration wave at the leading edge 5 will be completelymistimed.

As seen in FIGURE 2b the mis-timed Wave CA will arrive at the statorahead of the leading edge 6. This compression acceleration wave CAarrives too early at the high pressure outlet port D and caused a verystrong reflected wave CD to be propagated through the rotor as seen inFIGURE 2a. Again, as seen by comparison of FIGURES 2a and 2b thereflected Wave CD exists during -design speed operation and terminateson the trailing edge 8 of the high pressure inlet port C.

However, when the rotor speed is substantially reduced this reflectedwave CD will terminate ahead of the trailing edge 8, such as seen inFIGURE 2a. Since the reiiected wave CD has the effect of bothcompressing and modifying the velocity of the gases through which itwill pass its early arrival at the high pressure inlet port C, couldresult in a reversal of uid flow as seen in FIG- URE 2a. That is, theuid behind the reilected wave CD will now ow into the high pressureinlet port C as indicated by the arrow 50.

Furthermore, the early arrival of the reilected wave CD at the highpressure inlet port C will result in a second reflected wave ED whichwill have the effect of both dropping the pressure and reducing thevelocity of the uid through which it passes, hence when the secondreflected wave ED arrives at the high pressure outlet port D, there willagain be undesirable reversal of fluid from port D into rotor 30 such asindicated by arrow 5l.

The undesirable reversal of uid flowing between the high pressure inletport C at 50 and the high pressure outlet port D at 51 due to mis-timingwhen the rotor speed is decreased has been dealt with in the prior art.As seen in aforementioned co-pending application Serial Number 799,285the means to solve this reverse ow problem, consideration of changingthe location of both the leading and trailing edges of high pressureoutlet port D.

Although this prior art method has certain advantages for certainapplications of a pressure exchanger, there are other situations inwhich the 1re-location of both the leading and trailing edge of the highpressure outlet port D is not completely satisfactory due to the factthat it could be substantially reduced during extremely low rpm.operation of the pressure exchanger rotor.

My instant invention can be used in combination or in place of there-location of the edges of the high pres sure outlet port D. My instantinvention, however, is specifically directed to the modification of theconguration of the leading edges of the ports in the high pressureposition of the cycle.

In FIGURES 3a and 3b I have illustrated the conditions existing in thehigh pressure portion of the pressure exchanger cycle when the leadingedge of the high pressure outlet port D is modified in accordance withmy invention. It will be noted that the speed of the rotor in FIGURES 3aand 3b correspond to the speeds of the rotor illustrated in FIGURES 2aand 2b respectively.

Thus, it will be seen, in FIGURE 3a that the compression accelerationwave CA created at the leading edge 5 of the high pressure inlet port Cwill arrive at the stator 40 before the high pressure outlet port D iscompletely opened.

However, due to the flared surface 52 of the leading section of highpressure fluid ahead of the reflected wave CD will now be able to spillout into the high pressure outlet port D as illustrated by the arrow 53.That is,

f the wave CD, being a compression deceleration wave,

will compress the uid so that all fluid behind the wave is at higherpressure than the pressure ahead of the wave. Accordingly, in theembodiment seen in FIG- URE Za the fluid exisiting in the channelsstraddled by the waves CD and EA is at higher pressure than the fluidbehind the Wave EA or in front of the wave CD. Therefore, by aring thesurface 52 of the leading edge 6 of the high p-ressure outlet port D, asseen in FIG- URE 3a, the high pressure fluid straddled by the waves CDand EA will be permitted to spill out into the high pressure outlet portD. Furthermore, it will be noted that the Waves arriving at the extremeleft-hand end of the rotor 30 will not initially terminate on the solidsurface of the stator plate 40 and hence the magnitude of the reflectedwave CD will be substantially reduced.

It will be noted that with a substantial reduction of the magnitude ofthe reflected wave CD such as seen in FIGURE 3a that this reflected wavewill have less effect on the change in velocity than did the reflectedwave CD in the conditions noted above in connection with FIGURE 2a.Hence there will now merely be a reduction flow of fluid from this portC into the rotor 30, as illustrated by the arrow 54.

In like manner the reflected wave ED will, of necessity, be ofsubstantially reduced magnitude, .as compared to the 9 reflected Wave EDof FIGURE 2a. Hence the reflected wave ED will not result in a fluidflow reversal from the high pressure outlet port D into the rotor 30,but instead will merely cause a reduced flow into the high pressureoutlet port D from the rotor 30, as illustrated by the arrow 55.

Thus, it will be seen that by providing a modified configuration of theleading section for the high pressure outlet port D, such as aredportion 52, it is possible to eliminate or at least substantially reducethe undesirable flow reversal 50 and 51, as illustrated in FIGURE 2a andchange this to a mere reduction in fluid flows 54 and 55 as illustratedin FIGURE 2b.

It is noted that the basic concept of my instant invention can befurther adapted to the high pressure inlet port C to further improve thecondition by reduction of flow 54 and 55. To this end, I provide anarrangement as illustrated in FIGURES 4a and 4b whereby the leadingsection of the high pressure inlet port C, has a modified conguration,such as illustrated at 56. Thus in effect, when the channel of the rotor30 is approaching the leading edge 5 of the high pressure inlet port C,it will beV opened at 51 due to the stepped configuration section 56v topermit the introduction of some fluid from the high` pressure inlet portC to the rotor 30.

, Due to the throttling effect created by the shape of the opening edge5l of the port C, a compression acceleration wave CA of a lesserstrength will initially be created in this channel. The strength lofthis wave is less than the strength of the wave CA generated in the caseof instantly full opening shown in FIGURES 2 and 3. Therefore, thestrength of the reflected waves CD and EDv will be further reduced. f

As a result thereof, the reductions lof the ow from port C into therotor -30 behindthe wave CD, and the reduction of flow behind the waveED from the rotor 30 into the port D will be reduced to such an extent,that the speed of the rotor can be further reduced.

The shape of the opening'edge 56 of the high pressure gas inlet port Cshown in FIGURES 4a and 4b allows the port to open only to a certainlimited flow area. The shape is'so determined to provide a desired flowwhich in conjunction with the partial opening produces a first wave CA flesser strength then in the case of the instant full opening.

With the normal leading edge half of the flow area is open at the timethe rotor 30 has travelled half the distance of a blade partition. Withthe proposed shape however the channel only opens to a certain degreeand remains essentially constant for about rotation of the rotor. Onlythen the flow into the channel becomes fully unrestricted and the waveassumes full strength. This arrangement permits an improved performanceat 35% rotor speed, since the existence of a higher pressure in thechannel opposite the ramp 52 prevents the undesirable outiiow at lowspeed.

At normal operating speed the loss of performance due to the gasescaping at the modified edge of the intake port is insignificant.

Thus, in essence I have provided a novel arrangement whereby the leadingedge of the `high pressure outlet port D can have a modifiedconfiguration to result in a reduction of the magnitude of the reflectedwave which minimizes the undesirable effect of mis-timed waves at lowrotor speed.

Furthermore, the basic concept of my invention can vbe utilized at theleading edge of the high pressure inlet port C, to again minimize theundesirable effect of mis-timed waves at low rotor speed.

It is noted further, that my instant invention can be used inconjunction with or exclusive of the re-location of edges of the port tominimize the effect of mis-timed waves.

The tabulation of FIGURE 6 and the graphic illustration of FIGURE 6awill be used to summarize the char- Iacteristics of prior art devicescompared to my device. As seen in the conditions of curves 2, 3 and 4 ofFIGURE 6a and the tabulation of FIGURE 6, a constant speed aerodynamicwave machine does not operate at a maximum efficiency while deliveringthe mass flow `to the combustion engine over the full operating lspeedrange of the combustion engine. See aforementioned co-pending U.S.application Serial Number 637,570. In fact, this situation is stillfurther aggravated by a variable speed` aerodynamic wave machine as seenfor curves 5, 6, 7 wherein the deviation from required mass flow of thecombustion engine for variations in speed are even greater than in aconstant speed aerodynamic wave machine. By using an adjustable statorplate (condition l), it is possible to reestablish timing of the mainwaves to keep maximum efiiciency so that there will be an approximatelyconstant pressure output at the high pressure outlet port D as explainedvand described in aforementioned copending U.S. application SerialNumber 742,601. However, this method requires not only considerableadditional expense but also necessitates continuous adjustments therebyincreasing the possibility of malfunction.

Condition 8 is obtained with reduced size pick-up ports whereby `thestator plates 40 and 41 are stationary and a direct fixed ratio drivebetween the internal combustion engine and the pressure exchanger isused. The delivered airflow at of the maximum speed is only slightlyreduced to 98% of the flow with full size pick-up ports, with idealtiming conditions. However at 100% speed, maintaining the same engineexhaust gas temperature, the mistiming becomes more noticable and themass flow reduces to about 95%. At 50% rotor speed the losses due tomis-timing cause a reduction in mass ow to about of the mass flow whichis obtained with ideal wave timing. These conditions are `set forth inaforementioned copending application Serial Number 799,285 and shown inthe tabulation of FIGURE 6 as condition 8 and are also graphicallyillustrated in curve S in FIGURE 6a. It will be noted that thearrangement illustrated as condition 8 and curve 8 is superior inperformance to all other arrangements for 75% to 100% rotor r.p.m.except the adjustable plate illustrated as condition 1 and curve 1.However, the adjustable plate arrangement is a complicated mechanicalconstruction which increases the cost, increases mechanical failure,requires more maintenance and mechanical adjustments. This condition hasan efficiency which is slightly reduced over the range of speedoperation when compared to the more expensive and complicated adjustableplate arrangement, but has a consistently higher efficiency over the 75to 100% range of speed operation than all other prior art pressureexchangers even though there is no increase in either cost or mechanicalcomplexity.

Condition 9 of tabulation in FIGURE 6 and curve 9 of FIGURE 6a,represent the advantages achieved with my instant invention. It will benoted that under some operating conditions it is desirable to continueto produce high torque for speeds below 40% of maximum engine speed.Thus with my instant invention the percent of required mass flow at 75%to 100% of r.p.m. may be slightly reduced but is maintained slightlyabove conditions such as 8 at 35% r.p.m.

Thus I have provided a novel configuration of the leading edges of theports whereby the undesirable effects of the wave mis-timing can beminimized for low r.p.m. of the rotor to maintain a high pressure at thehigh pressure outlet port and also modify mass flow to substantiallymeet the requirements of a combustion engine.

Thus my invention is particularly adaptable to an aerodynamic Wavemachine (pressure exchanger) supercharging a reciprocating combustionengine wherein the combustion engine has the requirement of a hightorque over a wide speed range.

I claim:

1. A pressure exchanger being comprised of a rotor;

first and second stator plates positioned at opposite ends of saidrotor, said first stator plate having a high pressure outlet port andsaid second stator plate having a high pressure inlet port, one of saidstator plates also having a low pressure inlet port and the other ofsaid stator plates also having a low pressure outlet port; said highpressure inlet port providing a path for the introduction of a fluidunder high pressure into said rotor, and said high pressure outlet portbeing adapted t0 provide a path for the extraction of said Huid fromsaid rotor subsequent to the compression thereof by said pressureexchanger; said high pressure outlet port having a leading and atrailing edge adjacent its associated rotor end; said leading edge ofsaid high pressure outlet port being ared a predetermined amount, saidflared leading edge being adapted to eliminate reverse fluid flowthrough said high pressure outlet port so as to optimize extraction ofthe compressed fluid therethrough; the leading edge of said highpressure inlet port having a stepped configuration, said steppedconfiguration having a leading and a trailing edge, the trailing edge ofsaid stepped contiguration being the leading edge of said high pressureinlet port, the leading edge of said stepped configuration being apredetermined distance from the trailing edge and being adapted toreduce reverse uid ows at relatively low rotor operating speeds in orderto optimize extraction of fluid from said high pressure outlet port.

2. A pressure exchanger comprising a rotor assembly mounted for rotationthrough a predetermined speed range, said rotor having a plurality ofcells each extending longitudinally and substantially parallel with therotor axis of rotation; first and second stator plates positioned atopposite ends of said rotor, each being substantially parallel to theplane of rotation of said rotor; said first stator plate having a highpressure inlet port and a low pressure outlet port; said ports beingadapted to communicate with the cells of said rotor for introduction andextraction respectively of fluids in said rotor; said second statorplate having a high pressure outlet port and a loW pressure inlet port,said ports being adapted to communicate Withthe cells of said rotor forthe extraction and introduction respectively of fluids in said rotor;the high pressure outlet port of said second stator plate having aleading and a trailing edge, said high pressure outlet port beingpositioned relative to the high pressure inlet port of said first statorplate so as to permit extraction of high pressure fluid introduced intosaid high pressure inlet port subsequent to introduction and compressionof said fluid in said rotor cells; the leading edge of said highpressure outlet port being ared a predetermined amount, said flaredleading edge being adapted to eliminate reverse ilow of sai-d compressedfluid in order to maximize extraction of said compressed fluid at saidhigh pressure outlet port; the high pressure inlet port of said tirststator plate having a leading and a trailing edge, the leading edge ofsaid high pressure inlet port being positioned relative to the leadingedge of said high pressure outlet port so that a point on said rotorpasses the leading edge of said high prsesure inlet port a predeterminedtime prior to passing the. leading edge of said high pressure outletport, the

leading edge of said high pressure inlet port having a steppedconguration, said stepped configuration having leading and a trailingedge, the trailing edge of said stepped configuration being the leadingedge of said high pressure inlet port, the leading edge of said steppedconguration being a predetermined distance from the trailing edge,whereby a point on said rotor passes said stepped configuration leadingedge prior to passing said stepped configuration trailing edge; thestepped configuration being adapted to reduce reverse flow of fluid atsaid high pressure inlet port in order to maximize extraction ofcompressed uid at said high pressure outlet port during lowspeedoperation.

References Cited in the le of this patent UNITED STATES PATENTS2,780,405 Jendrassik Feb. 5, 1957 2,836,346 lendrassik May 27, 1958FOREIGN PATENTS 803,659 Great Britain Oct. 29, 1958 876,601 France Aug.10,- 1942 OTHER REFERENCES Germany (Application Ia/46f, Hl2,826, Feb. 2,1956.

1. A PRESSURE EXCHANGER BEING COMPRISED OF A ROTOR; FIRST AND SECONDSTATOR PLATES POSITIONED AT OPPOSITE ENDS OF SAID ROTOR, SAID FIRSTSTATOR PLATE HAVING A HIGH PRESSURE OUTLET PORT AND SAID SECOND STATORPLATE HAVING A HIGH PRESSURE INLET PORT, ONE OF SAID STATOR PLATES ALSOHAVING A LOW PRESSURE INLET PORT AND THE OTHER OF SAID STATOR PLATESALSO HAVING A LOW PRESSURE OUTLET PORT; SAID HIGH PRESSURE INLET PORTPROVIDING A PATH FOR THE INTRODUCTION OF A FLUID UNDER HIGH PRESSUREINTO SAID ROTOR, AND SAID HIGH PRESSURE OUTLET PORT BEING ADAPTED TOPROVIDE A PATH FOR THE EXTRACTION OF SAID FLUID FROM SAID ROTORSUBSEQUENT TO THE COMPRESSION THEREOF BY SAID PRESSURE EXCHANGER; SAIDHIGH PRESSURE OUTLET PORT HAVING A LEADING AND A TRAILING EDGE ADJACENTITS ASSOCIATED ROTOR END; SAID LEADING EDGE OF SAID HIGH PRESSURE OUTLETPORT BEING FLARED A PREDETERMINED AMOUNT, SAID FLARED LEADING EDGE BEINGADAPTED TO ELIMINATE REVERSE FLUID FLOW THROUGH SAID HIGH PRESSUREOUTLET PORT SO AS TO OPTIMIZE EXTRACTION OF THE COMPRESSED FLUIDTHERETHROUGH; THE LEADING EDGE OF SAID HIGH PRESSURE INLET PORT HAVING ASTEPPED CONFIGURATION, SAID STEPPED CONFIGURATION HAVING A LEADING AND ATRAILING EDGE, THE TRAILING EDGE OF SAID STEPPED CONFIGURATION BEING THELEADING EDGE OF SAID HIGH PRESSURE INLET PORT, THE LEADING EDGE OF SAIDSTEPPED CONFIGURATION BEING A PREDETERMINED DISTANCE FROM THE TRAILINGEDGE AND BEING ADAPTED TO REDUCE REVERSE FLUID FLOWS AT RELATIVELY LOWROTOR OPERATING SPEEDS IN ORDER TO OPTIMIZE EXTRACTION OF FLUID FROMSAID HIGH PRESSURE OUTLET PORT.